Exercise-Induced Hematuria in Athletes: Mechanisms, Differential Diagnosis, and Clinical Significance - A Narrative Review

Background. Blood in the urine after exercise is a frequent finding across running, swimming, cycling and contact sports, yet it remains poorly standardised in definition and often managed inconsistently between sports medicine and urology.Aim. To synthesise, from a clinically oriented perspective, the mechanisms, contributing factors, differential diagnosis and clinical significance of exercise-induced hematuria, and to propose a pragmatic framework distinguishing benign athletic pseudonephritis from pathology requiring urological work-up.Materials and Methods. Narrative review of peer-reviewed English-language cohort and observational studies, case reports and series, scoping and systematic reviews, and clinical guidance addressing hematuria, foot-strike hemolysis, athletic pseudonephritis and acute kidney injury in exercising populations.Results. Post-exercise hematuria is common, reported in roughly one-quarter to over half of participants after long-distance running and ultra-endurance events, arising from mechanical bladder trauma, glomerular and tubular stress, foot-strike hemolysis and myoglobinuria, and, in predisposed individuals, sickle cell trait, renal hypouricemia or urological malignancy. Most cases resolve within days without intervention, but red-flag features - persistence beyond one to two weeks, marked proteinuria, casts, flank pain, or hematuria unrelated to running intensity - warrant escalation.Conclusions. Exercise-induced hematuria is usually self-limited, reflecting adaptive and mechanical responses to strenuous exertion, but clinicians should maintain a structured, red-flag-driven approach to exclude underlying renal, urological or hematological disease, particularly in atypical presentations or at-risk populations.